Sister cities of New Haven, Connecticut

New Haven is the second-largest city in Connecticut after Bridgeport and the sixth-largest in New England with a population at the 2010 United States Census of 129,779 people. According to a census done by the Census Bureau as of July 1, 2012, the city had a population of 130,741, making it the second largest city in Connecticut. New Haven is the principal municipality in Greater New Haven, which had a total population of 862,477 in 2010. It is located on New Haven Harbor on the northern shore of Long Island Sound in New Haven County, which in turn comprises a part of the New York-Newark-Bridgeport, New York-New Jersey-Connecticut-Pennsylvania Combined Statistical Area.

New Haven was founded in 1638 by English Puritans, and a year later eight streets were laid out in a four-by-four grid, creating what is now commonly known as the "Nine Square Plan", now recognized by the American Institute of Certified Planners as a National Planning Landmark. The central common block is New Haven Green, a 16-acre (6 ha) square, now a National Historic Landmark and the center of Downtown New Haven.

New Haven is the home of the Ivy League school Yale University. The university is an integral part of the city's economy, being New Haven's biggest taxpayer and employer, as noted in the Mayor's 2010 State of the City address. Health care (hospitals and biotechnology), professional services (legal, architectural, marketing, and engineering), financial services, and retail trade also help to form an economic base for the city.

New Haven had the first public tree planting program in America, producing a canopy of mature trees (including some large elms) that gave New Haven the nickname "The Elm City".